Correspondence regarding the observation and photography of a fire phenomenon by Amanuens Erik Reuterswärd

This document is a letter dated August 2, 1946, from Professor Bertil Lindblad at the Stockholm Observatory in Saltsjöbaden to the Air Defense Department of the Swedish Defense Staff. The letter addresses a request for an assessment of a fire phenomenon that was observed and photographed by an amanuensis named Erik Reuterswärd. Professor Lindblad notes that the photograph is interesting, particularly due to the high intensity of the phenomenon observed over a very short period. However, he states that it is impossible to definitively rule out the possibility that the phenomenon was a meteor based on the available photographic and visual evidence. Lindblad suggests that a way to distinguish between meteors and exploding rocket-like projectiles would be to capture their spectra, as meteors possess characteristic line spectra. He mentions that Observator Öhman has developed a concept for a suitable surveillance camera for this purpose, which is provided in an accompanying memorandum. The letter concludes by returning the photograph to the Defense Staff.